Process for producing hydrogen, sulfur and sulfur dioxide from hydrogen sulfide-containing gas streams

Abstract

A process for making molecular hydrogen, elemental sulfur and sulfur dioxide from hydrogen sulfide. The process involves contacting a gas stream of hydrogen sulfide within a contacting zone with a contacting composition comprising metal sulfide in a lower sulfided state and yielding from the contacting zone a product gas stream comprising hydrogen and a recovered contacting composition comprising metal sulfide in a higher sulfided state. The higher metal sulfide is regenerated with oxygen to yield elemental sulfur and sulfur dioxide.

That which is claimed is: 
     
       1. A process for making hydrogen, sulfur and sulfur dioxide from hydrogen sulfide, wherein said process comprises:
 introducing a gas stream comprising hydrogen sulfide into a sulfidation zone, operated under suitable sulfidation conditions and containing a lower metal sulfide, and contacting therein said gas stream with said lower metal sulfide to thereby yield molecular hydrogen and a higher metal sulfide; 
 passing from said sulfidation zone a treated gas stream containing molecular hydrogen and having a reduced hydrogen sulfide concentration; 
 passing from said sulfidation zone said higher metal sulfide and introducing it into a regeneration zone; 
 introducing a sub-stoichiometric amount of molecular oxygen into said regeneration zone and contacting said higher metal sulfide with said molecular oxygen for a short contacting time to thereby convert said higher metal sulfide to said lower metal sulfide and to yield sulfur dioxide and elemental sulfur; 
 passing from said regeneration zone said lower metal sulfide and introducing it into said sulfidation zone; and 
 passing from said regeneration zone a regeneration zone effluent comprising sulfur dioxide and elemental sulfur. 
 
     
     
       2. A process as recited in  claim 1 , further comprising:
 condensing elemental sulfur from said regeneration zone effluent to yield a sulfur condenser effluent stream having a sulfur condenser effluent stream having a sulfur dioxide concentration and a reduced sulfur concentration. 
 
     
     
       3. A process as recited in  claim 2 , further comprising:
 passing said sulfur condenser effluent stream to a sulfuric acid production unit whereby the sulfur dioxide is used as a reactant for the production of sulfuric acid. 
 
     
     
       4. A process as recited in  claim 3 , wherein said lower metal sulfide is a metal sulfide selected from the group consisting of FeS, Fe 7 S 8 , NiS, Ni 2 S 3 , CoS, Co 9 S 8 , Sn 3 S 4 , Na 2 S, Na 2 S 2  and Na 2 S 3 . 
     
     
       5. A process as recited in  claim 4 , wherein said suitable sulfidation conditions include a sulfidation reaction temperature within said sulfidation zone that is in the range of from 150° C. to 700° C., a sulfidation reaction pressure in the range of from about atmospheric to about 13,840 kPa, and a molar ratio of said lower metal sulfide to H 2 S within said sulfidation zone is in the range of from 0.1:1 to 10:1. 
     
     
       6. A process as recited in  claim 5 , wherein said suitable regeneration conditions include a regeneration reaction temperature within said regeneration zone that is in the range of from 200° C. to 900° C., and a regeneration reaction pressure in the range of form about atmospheric to about 13,840 kPa. 
     
     
       7. A process as recited in  claim 6 , wherein said reduced hydrogen sulfide concentration of said treated gas stream is less than 100,000 ppmv (10 vol. %). 
     
     
       8. A process as recited in  claim 7 , wherein said sub-stoichiometric amount of molecular oxygen is less than 1. 
     
     
       9. A process as recited in  claim 8 , wherein the molar ratio of S to S plus SO 2  in said regeneration zone effluent is in the range of from 0.1 to about 0.95. 
     
     
       10. A process as recited in  claim 2 , wherein said lower metal sulfide is a metal sulfide selected from the group consisting of FeS, Fe 7 S 8 , NiS, Ni 2 S 3 , CoS, Co 9 S 8 , Sn 3 S 4 , Na 2 S, Na 2 S 2  and Na 2 S 3 . 
     
     
       11. A process as recited in  claim 10 , wherein said suitable sulfidation conditions include a sulfidation reaction temperature within said sulfidation zone that is in the range of from 150° C. to 700° C., a sulfidation reaction pressure in the range of from about atmospheric to about 13,840 kPa, and a molar ratio of said lower metal sulfide to H 2 S within said sulfidation zone is in the range of from 0.1:1 to 10:1. 
     
     
       12. A process as recited in  claim 11 , wherein said suitable regeneration conditions include a regeneration reaction temperature within said regeneration zone that is in the range of from 200° C. to 900° C., and a regeneration reaction pressure in the range of form about atmospheric to about 13,840 kPa. 
     
     
       13. A process as recited in  claim 12 , wherein said reduced hydrogen sulfide concentration of said treated gas stream is less than 100,000 ppmv (10 vol. %). 
     
     
       14. A process as recited in  claim 13 , wherein said sub-stoichiometric amount of molecular oxygen is less than 1. 
     
     
       15. A process as recited in  claim 14 , wherein the molar ratio of S to S plus SO 2  in said regeneration zone effluent is in the range of from 0.1 to about 0.95. 
     
     
       16. A process as recited in  claim 1 , wherein said lower metal sulfide is a metal sulfide selected from the group consisting of FeS, Fe 7 S 8 , NiS, Ni 2 S 3 , CoS, Co 9 S 8 , Sn 3 S 4 , Na 2 S, Na 2 S 2  and Na 2 S 3 . 
     
     
       17. A process as recited in  claim 16 , wherein said suitable sulfidation conditions include a sulfidation reaction temperature within said sulfidation zone that is in the range of from 150° C. to 700° C., a sulfidation reaction pressure in the range of from about atmospheric to about 13,840 kPa, and a molar ratio of said lower metal sulfide to H 2 S within said sulfidation zone is in the range of from 0.1:1 to 10:1. 
     
     
       18. A process as recited in  claim 17 , wherein said suitable regeneration conditions include a regeneration reaction temperature within said regeneration zone that is in the range of from 200° C. to 900° C., and a regeneration reaction pressure in the range of form about atmospheric to about 13,840 kPa. 
     
     
       19. A process as recited in  claim 18 , wherein said reduced hydrogen sulfide concentration of said treated gas stream is less than 100,000 ppmv (10 vol. %). 
     
     
       20. A process as recited in  claim 19 , wherein said sub-stoichiometric amount of molecular oxygen is less than 1. 
     
     
       21. A process as recited in  claim 20 , wherein the molar ratio of S to S plus SO 2  in said regeneration zone effluent is in the range of from 0.1 to about 0.95.